Can Laptop cards be used on Iphone 3g plan?

I'm thinking about switching to AT&T and was wondering if it was possible to use a laptop card on the same 3G plan that you use for the iphone. For instance, would I just be able to pop the sim out of the iPhone and put it into the laptop card temporarily? I don't really know anything about laptop cards and was thinking about getting one so I could have internet anywhere.

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